Joomla vs Drupal

What is Drupal?
Drupal is a content management framework, content management system and blogging engine which was originally written by Dries Buytaert and is the software used to power Debian Planet, Terminus1525, Spread Firefox and Kernel Trap, among others. Drupal is written in PHP using strict coding standards. (Wikipedia)

What is Joomla?
Joomla! is one of the most powerful Open Source Content Management Systems on the planet. It is used all over the world for everything from simple websites to complex corporate applications. Joomla! is easy to install, simple to manage, and reliable. (Joomla.org)